The present invention relates to a system, a method, and a program for evaluating or predicting costs such as the travel time along a certain route, energy consumption, and CO2 emission in a route on road networks.
In recent years, growing attention has been paid to predictive modeling of transportation traffic for better city planning. In this context, intelligent transportation systems (ITS) have been extensively studied particularly from the late 1990 s.
In ITS, systematically predicting the travel time along a route chosen is of crucial importance since approximately predicting the travel time of an arbitrary route is useful to reduce the energy and carbon footprint of a drive.
In addition to travel-time, predicting other types of costs such as energy consumption and CO2 emission along a route is often required in ITS. To predict the cost, the following conventional techniques are known.
Japanese Patent Application Publication No. 2002-367071 discloses a technique for collecting and recording links (roads each connecting intersections adjacent to each other), congestion level data at each time of day, and travel time data at each time of day in the section, which are necessary to determine an average speed at each congestion level, determining an arrival time at each link and its congestion level data at the time of day by using the average speed at each congestion level assumed based on the definition of the congestion level, calculating an average speed at each congestion level by using the congestion level data of each link at the determined arrival time for each link, dividing a congestion level length by each congestion level average speed by using the calculated average speed at each congestion level, and adding up the obtained values to find the travel time.
Japanese Patent Application Publication No. 2005-208791 discloses a road link travel time estimating device which finds an n-th order transformation function for calculating the travel time of individual road links based on a road link congestion level by using a relationship between the past road link travel time and a road link congestion level, finds an n+1 multiple regression equations for calculating the coefficients of the transfer function from road attribute information by performing a multiple regression analysis with the coefficient of the transformation function as a target variable and with the road attribute information as an explanatory variable, calculates the coefficient of the transformation function by assigning the road attribute information of the road link to be subjected to the road link travel time estimation to the multiple regression equations, applies the coefficient to the transformation function, and calculates an estimated value of the road link travel time by assigning the road link travel-jam level at the moving time to the transformation function.
Japanese Patent Application Publication No. 2008-282161 discloses a technique for calculating a coefficient of a first transform for calculating normalized link travel time by using a relationship between a calculated past link congestion level and the normalized link travel time, finding a regression equation by using a mixed model of multiple regression analysis and quantification theory class I analysis with the coefficients of the first transform as variables, calculating a coefficient of a second transform by applying the calculated congestion level to be subjected to travel time estimation to the regression equation, calculating an estimated value of the normalized link travel time to be subjected to the travel time estimation by applying the calculated coefficient to a second transform, and calculating an estimated value of the road link travel time on the basis of the normalized link travel time.
Although the technique disclosed in Japanese Patent Application Publication No. 2002-367071 provides a method for computing the travel time, it assumes that the average speed remains unchanged along a route (independently of the links) and such an assumption will be unrealistic. Therefore, satisfactory prediction accuracies are not expected from the method.
The techniques in Japanese Patent Application Publication No. 2005-208791 and its improvement, Japanese Patent Application Publication No. 2008-282161 are to predict the travel time on the basis of the congestion levels of the respective links. However, the assumption that the congestion level of all the links in a route is measurable strongly limits the utility of the method, or in some cases, may be too unrealistic to assume.